Athletic footwear may include uppers and sole structures. An upper may provide a covering for the foot that securely receives and positions the foot with respect to a sole structure. In particular, the upper may form an interior void that has the general shape of the foot. Access to the void may be provided at an ankle opening. The upper may extend over the instep and toe areas of the foot, along the medial and lateral sides of the foot, and around the heel region of the foot. A lacing system or other closure device may be incorporated into the upper and allow selective changes to the size of the ankle opening, thereby permitting a wearer to modify girth and other dimensions of the upper to accommodate feet of varying proportions.
A sole structure may be secured to a lower surface of the upper and generally positioned between a wearer foot and the ground (or other contact surface). The sole structure may incorporate an insole, a midsole, and/or an outsole. The insole (which also may constitute a sock liner) may be a thin member located within the upper and adjacent the plantar (lower) surface of the foot to enhance footwear comfort, e.g., to wick away moisture and provide a soft, comfortable feel. The midsole may be attached to the upper and form a middle layer of the sole structure. The outsole may form the ground-contacting element of footwear and be fashioned from a durable, wear-resistant material that includes texturing and/or other features to improve traction.
In addition to attenuating ground reaction forces, providing traction and protecting a foot from a contact surface or objects thereon, a sole structure may potentially control harmful foot motion. There remains a need for sole structures that include elements able to provide such control.